A conventional yoke unit 300 is described by referring to FIG. 19. The yoke unit 300 includes a first yoke 310, a second yoke 320, and a resin section 330. The first yoke 310 includes multiple first magnetic pole teeth 311, a first yoke core 312, and a through hole 313. The through hole 313 is formed in the first yoke core 312. The second yoke 320 includes multiple second magnetic pole teeth 321, a second yoke core 322, and a through hole 323. The through hole 323 is formed in the second yoke core 322. The first and second yokes 310 and 320 are coaxial with each other. Each of the second magnetic pole teeth 321 is arranged between two adjacent ones of the first magnetic pole teeth 311. The resin section 330 makes the first and second yokes 310 and 320 integral with each other. Patent Document 1 discloses an example of the conventional yoke unit.
A method of manufacturing the yoke unit 300 is described by referring to FIG. 20.
The yoke unit 300 is manufactured using a pin 500 and a lower mold 400, for example. First, the pin 500 is inserted into the through holes 323 and 313 in this order. This determines the respective positions of the first and second yokes 310 and 320 in the circumferential direction relative to the lower mold 400. Next, molten resin is poured into a space between a mold (not shown in the drawings) arranged around the lower mold 400 and the lower mold 400. Then, the molten resin is cured to shape the resin section 330.
The respective positions of the first and second yokes 310 and 320 in the circumferential direction are determined using the through holes 313 and 323. Hence, an error in the position of the through hole 313 or 323 might reduce the accuracy in the respective positions of the first and second yokes 310 and 320.